1. Field of the Invention
This invention relates generally to audio switching amplifiers and, more particularly, to audio switching amplifiers that produce an audio output signal as a result of pulse width modulation. This type of audio amplifier can produce irritating noise when the amplifier is turned on or off.
2. Discussion of the Related Art
In power switching amplifiers that are used for audio sound reproduction, such as would be used in an automobile radio, undesirable audio components have been encountered during the turn-on and turn-off operation. The power switching amplifier is subjected to transient voltage conditions that can result in a signal being applied to the speaker having random components. To eliminate this source of undesirable sound or noise, apparatus has been used to silence or mute the output signal of the power amplifiers applied to the speakers during these transient conditions.
A need has therefore been felt for a circuit to mute the output of the power switching amplifier during turn-on and turn-off conditions of the circuit that is both effective in reducing undesired components in the output signal of the power amplifier units and easily implemented.